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RenderMan for Maya automatically establishes the correct rendering context for variations in particle color, opacity, and radius. A useful way to attach the particle's color and opacity, is to use the Cs and Ci primvars. You can attach the primvars to the material by using a PxrPrimvar pattern.

You can write MEL expressions to calculate per-particle radii (radiusPP), color (rgbPP), opacity (opacityPP), and lifespan (lifespanPP and useLifespanPP). You can also use Maya to setup procedural ramps which remap these values.

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